The jasmonate‐responsive AaMYC2 transcription factor positively regulates artemisinin biosynthesis in Artemisia annua

Abstract

SummaryThe plant Artemisia annua is well known due to the production of artemisinin, a sesquiterpene lactone that is widely used in malaria treatment. Phytohormones play important roles in plant secondary metabolism, such as jasmonic acid (JA), which can induce artemisinin biosynthesis in A. annua. Nevertheless, the JA-inducing mechanism remains poorly understood.The expression of gene AaMYC2 was rapidly induced by JA and AaMYC2 binds the G-boxlike motifs within the promoters of gene CYP71AV1 and DBR2, which are key structural genes in the artemisinin biosynthetic pathway.Overexpression of AaMYC2 in A. annua significantly activated the transcript levels of CYP71AV1 and DBR2, which resulted in an increased artemisinin content. By contrast, artemisinin content was reduced in the RNAi transgenic A. annua plants in which the expression of AaMYC2 was suppressed. Meanwhile, the RNAi transgenic A. annua plants showed lower sensitivity to methyl jasmonate treatment than the wild-type plants.These results demonstrate that AaMYC2 is a positive regulator of artemisinin biosynthesis and is of great value in genetic engineering of A. annua for increased artemisinin production.

Transcriptome Analysis of JA Signal Transduction, Transcription Factors, and Monoterpene Biosynthesis Pathway in Response to Methyl Jasmonate Elicitation in Mentha canadensis L.

“…Compared with well-studied metabolic pathways such as flavonoids, the transcriptional regulation of terpene metabolism has been validated in a few studies. Several TFs have been identified from plants including A. annua (AaWRKY1, AaERF1, AaERF2, AabZIP1, and AaMYC2), Gossypium arboretum (GaWRKY1), Taxus chinensis (TaWRKY1), Hevea brasiliensis (EREBP1 and HbWRKY1), and O. sativa (OsTGAP1) that regulate terpene biosynthesis [21,22,23,42,43,44,45,46,47,48]. In Mentha species M. spicata , two TFs MsYABBY5 and MsMYB ( M. spicata MYB DNA-binding protein) have been reported that negatively regulate monoterpene production [49,50].…”

Transcriptome Analysis of Genes Associated with the Artemisinin Biosynthesis by Jasmonic Acid Treatment under the Light in Artemisia annua

“…But the transcriptional regulation mechanism is not clear. In recent years, there have been characterized several TFs which could directly bind to the promoters of the aretmisinin biosynthetic genes and regulate the artemisinin content in A. annua (Ma et al, 2009; Yu et al, 2012; Lu et al, 2013a; Shen et al, 2016). Furthermore, a novel TF, AaHD1 (HOMEODOMAIN PROTEIN 1), which belongs to the homeodomain-leucine zipper TF family was identified by our lab (Yan et al, 2016).…”

“…Artemisia annua used in this study was “Huhao 1,” which obtained from Chongqing, China and developed in Shanghai after years of selection (Shen et al, 2016). A. annua seeds were sown in pots filled with compost and placed in a growth chamber under the growth condition described previously (Zhang et al, 2015).…”

“…Furthermore, JA-responsive AaERF1 and AaERF2 could positively regulate the transcription of AaADS and AaCYP71AV1 , and increased the accumulation of artemisinin and artemisinic acid in the overexpressed transgenic A. annua plants (Yu et al, 2012; Lu et al, 2013a). In addition, overexpression of JA-responsive AaMYC2 in A. annua significantly activated the transcription of AaCYP71AV1 and AaDBR2 , and resulted in the increase of artemisinin content (Shen et al, 2016). …”

Plant Metabolic Engineering Strategies for the Production of Pharmaceutical Terpenoids

“…Compared with the WT, overexpression of AaMYC2 significantly increased the content of artemisinin and DHAA in transgenic A. annua . Meanwhile, the content of artemisinic acid, which was the competitive pathway product, was significantly reduced in AaMYC2 overexpressing lines (Shen et al, 2016). …”